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8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10)

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FICTIONAL SAMPLE - Contoso Renewables, Quellmoor Ridge Wind Farm and every organisation, person, product and value in this wiki are invented. Not for operational use.

This is an 8D incident report for repeated gearbox oil over-temperature on WTG-07. It covers the team, problem description, containment, root-cause analysis, corrective and preventive actions, verification status, and open closure condition.

Key facts

  • The 2026-07-10 revision has D1 to D7 complete and D8 open until the bearing replacement.1
  • The report number is INC-2026-006.2
  • The incident concerns WTG-07, serial LT32-19-0421, with gearbox FGT-3200-18-07752.3
  • The report was opened on 2026-05-30 after the first A2102 trip.4
  • Yusuf Arkwell, Reliability Engineer, is the 8D lead.5
  • Between 2026-04-09 and 2026-06-21, WTG-07 logged 27 A2101 warnings at 75 °C and two A2102 trips at 82 °C, while no other turbine logged an A2101 warning in that period.6
  • The HSS bearing vibration on the generator side rose from 2.1 mm/s RMS to 5.2 mm/s RMS and exceeded the 4.5 mm/s alarm level.7
  • From 2026-06-01, WTG-07 was limited to 2.6 MW by the park controller with daily oil-temperature checks, and the limit was removed on 2026-06-25 after the D6 corrective actions.8
  • The root-cause analysis says the oil overheated because the oil cooler did not reject enough heat at high load.9
  • The cooler fan ran at reduced speed and the radiator fins were about 40 % blocked by insects and pollen.10
  • The fan motor LWS-P-30418 bearing had failed and the motor current was 35 % above nominal.11
  • The report identifies the root cause as missing preventive maintenance of the oil cooler, allowing fan motor bearing failure and radiator fouling to reduce cooling capacity.12
  • A contributing factor was generator-side HSS bearing wear, supported by oil analysis TR-OA-2026-0614 with iron at 64 ppm, PQ index 112, and the vibration trend.13
  • Corrective actions completed on 2026-06-24 included replacing oil cooler fan motor LWS-P-30418 under WO-26-0398 and cleaning the oil cooler radiator under WO-26-0399.1415
  • The 2.6 MW limit was removed after verification on 2026-06-25.16
  • Replacing the generator-side HSS bearing FGT-P-22328 under WO-26-0412 is waiting for parts and is planned on delivery of the bearing.17
  • Preventive task MP-GBX-07 for oil cooler radiator cleaning and fan current check was added to the maintenance plan for all turbines every 6 months.18
  • Minimum stock of fan motor LWS-P-30418 was raised from 1 to 2.19
  • A request to Litware Wind Systems to add fan motor current to SCADA signals is open under ticket LWS-TS-51877.20
  • Verification reports no A2101 warning on WTG-07 since 2026-06-24, but vibration remains above the alarm level until the bearing is replaced.21
  • The 8D remains open and will be closed after WO-26-0412 and an oil sample 500 operating hours after the bearing replacement.22

Contents

Report status and metadata

The report is titled as an 8D report for repeated gearbox oil over-temperature on WTG-07.23

The revision dated 2026-07-10 records D1 to D7 as complete and D8 as open until the bearing replacement.24

Table t01 · table 1, rows 1–5

RowFieldValue
2Report numberINC-2026-006
3TurbineWTG-07 (serial LT32-19-0421, gearbox FGT-3200-18-07752)
4Opened2026-05-30 after the first A2102 trip
58D leadYusuf Arkwell, Reliability Engineer

Agents can query this table as t01 with the query_table tool.

D1 - Team

The team consisted of Yusuf Arkwell as lead, Dario Penwarden, Callum Rydings, Élise Ternaux, Katrin Ostermeier from Fabrikam Getriebetechnik GmbH for remote support, and Imogen Thackwray from Trey Research Laboratories for oil analysis.25

D2 - Problem description

Between 2026-04-09 and 2026-06-21, WTG-07 logged 27 A2101 warnings and two A2102 trips, with no other turbine logging an A2101 warning in the same period.26

The generator-side HSS bearing vibration rose from 2.1 mm/s RMS on 2026-01-05 to 5.2 mm/s RMS on 2026-06-15, above the alarm level of 4.5 mm/s.27

Figure 1 is identified as showing WTG-07 weekly A2101 warnings and HSS bearing vibration for 2026.28

D3 - Containment

From 2026-06-01, WTG-07 was limited to 2.6 MW by the park controller and oil temperature was checked daily; the limit was removed on 2026-06-25 after the D6 corrective actions.29

D4 - Root cause analysis (5 Whys)

The analysis states that the oil overheated because the oil cooler did not reject enough heat at high load.30

The cooler fan ran at reduced speed and the radiator fins were about 40 % blocked by insects and pollen.31

The fan ran slowly because the bearing of fan motor LWS-P-30418 had failed, and the motor current was 35 % above nominal.32

The issue was not detected earlier because fan motor current was not monitored by SCADA and the radiator was cleaned only when found dirty.33

The maintenance plan followed a manual that gave no radiator cleaning interval and specified cleaning only as required.34

The stated root cause was missing preventive maintenance of the oil cooler, allowing fan motor bearing failure and radiator fouling to reduce cooling capacity.35

A contributing factor was generator-side HSS bearing wear confirmed by oil analysis TR-OA-2026-0614 and the vibration trend, which increased gearbox friction losses.36

D5 and D6 - Corrective actions

Table t02 · table 2, rows 1–5

RowActionWork orderOwnerDateStatus
2Replace oil cooler fan motor LWS-P-30418WO-26-0398Callum Rydings2026-06-24done
3Clean oil cooler radiatorWO-26-0399Élise Ternaux2026-06-24done
4Remove the 2.6 MW limit after verification-Dario Penwarden2026-06-25done
5Replace HSS bearing, generator side (FGT-P-22328)WO-26-0412Callum Rydingson delivery of the bearingwaiting for parts

Agents can query this table as t02 with the query_table tool.

D7 - Prevent recurrence

Task MP-GBX-07, for oil cooler radiator cleaning and fan current check, was added to the maintenance plan for all turbines every 6 months.37

The minimum stock of fan motor LWS-P-30418 was raised from 1 to 2.38

A request to Litware Wind Systems to add fan motor current to SCADA signals is open under ticket LWS-TS-51877.39

Verification found no A2101 warning on WTG-07 since 2026-06-24, while vibration remains above the alarm level until the bearing is replaced.40

D8 - Closure

The report remains open and will be closed after WO-26-0412 and an oil sample 500 operating hours after the bearing replacement.41

Figures

  • Figure f01 (¶ 8): Generated description: A dual-axis time series chart shows A2101 warnings per week as orange bars and Velocity RMS (mm/s) as a blue line with circular markers. The left y-axis is labeled A2101 per week from 0 to 6, and the right y-axis is labeled mm/s RMS from 0 to 7; two horizontal dashed reference lines appear at about 3 and 3.9. The blue line rises steadily from about 2.1 mm/s in early January to a peak near 5.4 mm/s in late June, while the orange bars begin in late March and increase to around 4 warnings per week by late May and June.42

Sources

Footnotes

  1. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 2 · ✓ quote verified ↩

  2. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — table 1, row 2 · table ↩

  3. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — table 1, row 3 · table ↩

  4. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — table 1, row 4 · table ↩

  5. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — table 1, row 5 · table ↩

  6. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 6 · ✓ quote verified ↩

  7. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 7 · ✓ quote verified ↩

  8. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 10 · ✓ quote verified ↩

  9. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 12 · ✓ quote verified ↩

  10. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 13 · ✓ quote verified ↩

  11. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 14 · ✓ quote verified ↩

  12. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 17 · ✓ quote verified ↩

  13. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 18 · ✓ quote verified ↩

  14. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — table 2, row 2 · table ↩

  15. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — table 2, row 3 · table ↩

  16. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — table 2, row 4 · table ↩

  17. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — table 2, row 5 · table ↩

  18. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 21 · ✓ quote verified ↩

  19. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 22 · ✓ quote verified ↩

  20. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 23 · ✓ quote verified ↩

  21. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 24 · ✓ quote verified ↩

  22. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 26 · ✓ quote verified ↩

  23. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 1 · paraphrase ↩

  24. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 2 · paraphrase ↩

  25. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 4 · paraphrase ↩

  26. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 6 · paraphrase ↩

  27. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 7 · paraphrase ↩

  28. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 8 · paraphrase ↩

  29. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 10 · paraphrase ↩

  30. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 12 · paraphrase ↩

  31. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 13 · paraphrase ↩

  32. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 14 · paraphrase ↩

  33. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 15 · paraphrase ↩

  34. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 16 · paraphrase ↩

  35. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 17 · paraphrase ↩

  36. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 18 · paraphrase ↩

  37. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 21 · paraphrase ↩

  38. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 22 · paraphrase ↩

  39. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 23 · paraphrase ↩

  40. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 24 · paraphrase ↩

  41. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 26 · paraphrase ↩

  42. 8D report INC-2026-006 - Repeated gearbox oil over-temperature on WTG-07 (revision 2026-07-10) — ¶ 8 · generated description ↩

Provenance badges✓ quote verified the quoted words were found verbatim in the source textparaphrase reworded from the source text; numbers checked, no verbatim quotetable values parsed deterministically from the cited table rowsgenerated description written by a model to describe a figure; not a quote

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